Quiz
Tap a question to see the answer
1. Which two senses make up most of what we call flavor?
Taste on the tongue and smell in the nose (Figure 1).
2. Name the five basic tastes.
Sweet, sour, salty, bitter and umami (Figure 2).
3. Is the tongue map, with sweet at the tip and bitter at the back, correct?
No; every area with taste buds senses all five tastes (Figure 2).
4. How many receptors sense sweet, and how many sense bitter?
One sweet receptor (T1R2 + T1R3) and about 25 bitter receptors (Figure 3).
5. Why do some people find broccoli and grapefruit very bitter?
They carry a receptor variant (TAS2R38) that makes them strong bitter tasters (Figure 3).
6. What do sour cells actually detect?
Hydrogen ions released by acids, entering through the OTOP1 channel (Figure 4).
7. Why do potassium chloride salt substitutes taste bitter?
Potassium does not fit the sodium channel well and also activates bitter cells (Figure 4).
8. What molecule causes umami taste, and what boosts it?
Free glutamate; inosinate and guanylate boost it strongly (Figure 5).
9. How does the sodium in MSG compare with table salt?
MSG has about a third as much sodium (Figure 5).
10. Which receptor does menthol switch on, and what does it normally sense?
TRPM8, the cold receptor (Figure 6).
11. Can the same vanillin molecule be natural or artificial?
Yes; the label depends on the source: from a plant via fermentation it can be natural, from petroleum guaiacol it is artificial (Figure 7).
12. Can a food containing yeast extract claim “No MSG”?
No; yeast extract is a natural source of free glutamate (Figure 8).